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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 27 (1988), S. 3846-3849 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 27 (1988), S. 3438-3446 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 103 (1988), S. 191-204 
    ISSN: 1432-1424
    Keywords: voltage-dependent K+ channel ; TEA+ ; barium ; circuit analysis ; cable analysis ; current-voltage relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of short (1 sec) and long (1 min) transepithelial current clamps on membrane voltages and resistances ofNecturus gallbladder were investigated. Transepithelial and cell membrane current-voltage relationships determined from 1-sec clamps revealed that: a) depolarization of the apical membrane voltage (V mc) results in a marked decrease in apical membrane fractional resistance (fR a), whereas hyperpolarization ofV mc results in either no change infR a or a small increase, and b) the voltage-dependent changes infR a are essentially complete within 500 msec. Exposure of the tissue to 5mm TEA+ on the mucosal side caused no significant change in baselineV mc (−69±2 mV) and yet virtually abolished the voltage dependence offR a. A possible interpretation of these results is that two types of K+ channels exist in the apical membrane, with different voltage dependencies and TEA+ sensitivities. Acidification or Ba2+ addition to the mucosal solution also reduced the voltage-dependent changes infR a. The time courses of the changes infR a and in the cable properties of the epithelium were assessed during 1-min transepithelial current clamps (±200 μA/cm2). No secondary change infR a was observed with mucosa-to-serosa currents, but a slow TEA+-sensitive decrease infR a (half-time of seconds) was evident with serosa-to-mucosa currents. Cable analysis experiments demonstrated that the initial (〈500 msec) voltage-dependent decrease infR a is due to a fall in apical membrane resistance. The later decrease infR a is due to changes in both cell membrane resistances attributable to the increase in transcellular current flow resulting from a fall in paracellular conductance. The voltage dependence of the apical membrane conductance is a more significant problem in estimatingfR a than the current-induced effects on the lateral intercellular spaces. In principle, TEA+ can be used to prevent the nonlinear behavior ofR a during measurements of the voltage divider or membrane resistance ratio.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 102 (1988), S. 163-174 
    ISSN: 1432-1424
    Keywords: chloride transport ; equivalent circuit ; cable analysis ; fluid transport ; ouffers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of bathing solution HCO 3 − /CO2 concentrations on baseline cell membrane voltages and resistances were measured inNecturus gallbladder epithelium with conventional intracellular microelectrode techniques. Gallbladders were bathed in either low HCO 3 − /CO2 Ringer's solutions (2.4mm HCO 3 − /air or 1mm HEPES/air) or a high HCO 3 − /CO2 Ringer's (10mm HCO 3 − /1% CO2). The principal finding of these studies was that the apical membrane fractional resistance (fR a) was higher in tissues bathed in the 10mm HCO 3 − /CO2 Ringer's, averaging 0.87±0.06, whereasfR a averaged 0.63±0.07 and 0.48±0.08 in 2.4mm HCO 3 − and 1mm HEPES, respectively. Intraepithelial cable analysis was employed to obtain estimates of the individual apical (R a) and basolateral membrane (R b) resistances in tissues bathed in 10mm HCO 3 − /1% CO2 Ringer's. Compared to previous resistance measurements obtained in tissues bathed in a low HCO 3 − /CO2 Ringer's, the higher value offR a was found to be due to both an increase inR a and a decrease inR b. The higher values offR a and lower values ofR b confirm the recent observations of others. To ascertain the pathways responsible for these effects, cell membrane voltages were measured during serosal solution K+ and Cl− substitutions. The results of these studies suggest that an electrodiffusive Cl− transport mechanism exists at the basolateral membrane of tissues bathed in a 10mm HCO 3 − /1% CO2 Ringer's, which can explain in part the fall inR b. The above observations are discussed in terms of a stimulatory effect of solution [HCO 3 − /PCO2 on transepithelial fluid transport, which results in adaptive changes in the conductive properties of the apical and basolateral membranes.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of business finance & accounting 15 (1988), S. 0 
    ISSN: 1468-5957
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Chitinolytic bacteria were enumerated and isolated from marine waters and sediments along the highly productive Antarctic Peninsula. Chitinolytic bacteria were found in low concentrations (approximately 1 cell per ml) in the water column and at much higher levels in marine surface sediments (104–105 per g). The predominant chitinolytic bacteria isolated from the water column were identified as psychrophilic Vibrio spp. Rates of chitin mineralization were measured by collection of 14CO2 respired from 14C-labeled chitin synthesized from chitosan and [1-14C]acetic anhydride. Chitin mineralization rates were extremely low in the marine waters analyzed (0.00085–0.0019% of the added label respired in 48 h) and appreciably higher in the marine sediments (0.0039–0.01% per 48 h), suggesting that the sediments are much more important in chitin degradation. Such low mineralization rates suggest that chitin may be accumulating in Antarctic marine sediments, though animals may also play an important role in chitin degradation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 24 (1988), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The Pawtuxet River flows from a relatively rural area through some of the more highly industrialized sections of Rhode Island. During its journey, the river receives many municipal, industrial, and ground water sources of metal constituents. The present report is the first in a two part series in which the water quality of this urban river was evaluated by a chemical monitoring study of the sources, transport mechanisms, and fate of cadmium, chromium, copper, lead, and nickel in the river. The second paper will use the chemical data to derive and calibrate a steady-state water quality model for this river.The metal concentrations In the river tended to increase from the headwaters to the mouth with river stations nearest to point source outfalls showing elevated values. In some sections of the river, levels of a few of the metals could not be explained by the point sources; and other inputs, including sediment resuspension, axe proposed to make up this apparent unbalance. The ability of a municipal secondary treatment plant to remove metals was demonstrated, and the tie-in of the effluent from a major chemical company to the plant did not cause any observable deterioration in treatment efficiency.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1352-1356 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An electron-paramagnetic-resonance (EPR) reference-arm microwave bridge is described that incorporates a FET microwave amplifier and a balanced quadrature mixer. An automatic frequency control (AFC) circuit is described that employs 70-kHz frequency modulation of the oscillator. AFC feedback is based on formation of the sum of squares of the I and Q outputs of the mixer using analog devices. The resulting AFC circuit is independent of the phase angle α of the reference-arm microwave voltage with respect to the signal-arm microwave voltage at the mixer. An L-band bridge is described that incorporates the circuit. Good AFC lock was obtained from 1 μW to 100 mW of incident power independent of α using a loop-gap resonator of Q=500.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 60 (1988), S. 2244-2248 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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